Gate-to-Gate Melt Transfer
Increasingly more popular is the melt transfer through the first mold parting surface without a sprue bar because it eliminates the sprue bar as an obstacle. The basic principle of a “sprue-bar-less” melt transfer is a nozzle-to-nozzle melt transfer.
As the mold parting surfaces close, two nozzle front ends establish a melt passage. These nozzles separate when the mold opens. A leak free connection or seal at 2000 bar or 30,000 psi is accomplished with the specially designed manifold system for stack molds from Mold Hotrunner Solutions®. During mold opening, the transfer nozzles provide a dry surface with absolutely no stringing or drooling of the melt.
A fully automated 24/7 molding operation with stack molds requires a functional melt transfer which operates over millions of cycles.
Sequentially controlled stack mold valve gate manifold with a four nozzle valve gate to valve gate melt transfer through the mold parting line featuring cooling free Black Box™ actuators
Generally, flat parts are more suitable for stack mold consideration than are deep core parts because of the machine opening stroke and the increased mold height of a stack mold. It is also important to check the shot capacity of the machine barrel ensuring that the injection unit can supply enough melt volume cycle for cycle and for all cavities.
MHS stack molds using Rheo-Pro® hot runner systems have a long track record for application success in thin wall packaging, caps and closures, containers and lids, collapsible crates, trays, panels, grills and large surface parts for appliances.
Tandem MoldingFill analysis for Tandem molded washer components with metal insert molding, valve-to-valve melt transfer through part center hole. First part weight 3.6kg, second part 1.0kg
Tandem molding is a type of stack molding process in which the parts are injected in alternating cycles. While the molding machine opens to demold one parting line, the other is held together by a locking system. The technology can be employed in almost any standard injection molding machine and offers all of the benefits of stack molding as well as extended cooling times.
Part A Cooling
Part B Filling
Part A Filling
Part B Cooling
Compact iVG™ Valve Gate Stack Molds
16+16 Rheo-Pro® iVG™ back-to-back valve gate hot half featuring fully front accessible nozzles (with integrated actuators) for medical syringe plungers
The Rheo-Pro® iVG™ is an internal actuated valve gate system with no external cyclinder and no elastomeric seals. It requires no cooling. iVG™ represents the latest and most innovative valve gate technology in the industry and is ideal for compact, reliable stack mold solutions.
Cooling-Free Valve Gating
Black Box™ and iVG™ hot runners represent a new generation of valve gate systems that does not require maintenance during the life of the mold. These systems eliminate all quality issues related to cooling water such as corrosion and contamination. Less plumbing also simplifies the design and assembly of the mold. New cooling-free technology can benefit all valve gate applications, including high temperature plastics such as PEEK, LCP, PSU, PEI, and PPS, known for their special properties. Processing these materials requires high melt temperatures of up to 450°C in the hot runner and mold temperatures of over 200°C. Black Box™ and iVG™ hot runner systems deliver uninterrupted performance under extreme conditions without cooling or wear. The result is a significant increase in reliability and mold uptime.